1. Technical Field
The present invention relates to methods and systems for the detection of leakage in fluid pipelines. More specifically, the present invention relates to optical methods and systems to detect such leakages.
2. Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
Extensive pipeline networks are relied upon for the transportation and delivery of water. One major problem frequently encountered by engineers and municipal authorities is water leakage from these water pipelines. There are several reasons for water to leak from a pipeline, for example, loose pipe fittings, damage from excessive fluid pressure and corrosion caused by reactions with the moving fluid or a surrounding medium. Globally and especially in arid regions, water is a scarce resource and desalination of sea water is widely pursued in order to cope with the demand of growing populations and to support expanding economies. Hence, it is very important to detect pipeline leakages since they may present serious environmental and economic problems. Current pipeline monitoring systems lack responsiveness and often report the problem only after significant amounts of fluid have been spilled.
The pressure built within a pipeline of flowing water is mainly attributed to pumping. When a pipe leaks, it causes a sudden drop in pressure, and the pressure fluctuation sends an acoustical signal in both upstream and downstream directions. Acoustics-based methods have been conventionally used by engineers to detect pipeline leakages. Microphones and/or hydrophones are used to pick up sounds generated by leaking fluids. Cross-correlations of two signals from the two upstream and downstream measuring points provide distance measurements of the leak from the measuring points and thus, the location of the leak can be determined by calculations.
Another acoustic method of leak detection is the utilization of ultrasonic signals. In one scenario, an ultrasonic wave is sent in the pipe walls and the incidental wave is scattered when it encounters a discontinuity (leak domain). The transmitted or reflected ultrasonic wave is measured to indicate the type of discontinuity encountered. In another scenario, an ultrasonic signal is generated by a transmitter and sent across the pipe. The ultrasonic signal is then received by a transducer to examine the signal's distortion, which is an indicator of any entrainment due to leakage.
Other electromagnetic and optical fiber-based methods have also been employed to detect leakages in water pipeline systems. Each method comes with its respective pros and cons.
Optical methods have been utilized for the detection of natural gas leakage from pipes. Various optical systems based on monitoring light absorption or scattering of emitted radiation have been described, including light detection and ranging (LIDAR) systems (Minato A, Joarder M, Ozawa S, Kadoya M, Sugimoto N, 1999. Development of a LIDAR system for measuring methane using a gas correlation method. Jpn J Appl Phys Part 1 38(10): 6130-6132—incorporated herein by reference in its entirety), diode laser absorption system (Iseki T, Tai H, Kimura K, 2000. A portable remote methane sensor using a tunable diode laser. Measurement Science and Technology 11: 594—incorporated herein by reference in its entirety), CO2 laser backscatter imaging systems (Kasai N, Tsuchiya C, Fukuda, T, Sekine K, Sano T, Takehana T, 2011. Propane gas leak detection by infrared adsorption using carbon infrared emitter and infrared camera. NDT and E International 44(1): 57-60; Kulp T, Kennedy R, Delong M, Garvis M, Stahovec J, 1993. The development and testing of a backscatter absorption gas imaging system capable of imaging at a range of 300 m. Applied Laser Radar Technology, Proc. Soc. Photo-Opt. Instrum. Eng 1936: 204-212—each incorporated herein by reference in its entirety) and broadband absorption systems (Spaeth L, O'Brien M, 2003. An additional tool for integrity monitoring. Pipeline and gas journal 230(3): 41—incorporated herein by reference in its entirety).
The use of multiple techniques for the detection of water leakage in pipelines can provide more reliable results leading to a more accurate engineering decision. It will be desirable to combine different leak systems based upon different principles of physics. Therefore, it becomes necessary to design methods and systems other than the aforementioned acoustic, ultrasonic, electromagnetic and optical fiber-based methods and systems that can accurately detect leakages in water pipeline systems and are efficient in terms of response time, sensitivity, robustness and cost.